'Alt Charge' Light on Dash

Possible, but unlikely if this only occurs when there is a second charging source.

Easy to check with shore power and generator off, engine at high idle. Check voltage at batteries with digital voltmeter. 13.5+, and generally 14 and there is no problem.

For what it's worth dept……
I have a 2000 HR Ambassador and according to the chassis wiring diagram, one side of the "ALT FAIL" bulb goes to +12V and the other side of the bulb goes to the alternator terminal L. If the alternator does not put out any volts (L terminal at ground level), the ALT FAIL light will light. So it is possible the OP had a legitimate alternator failure.

Richard

Thanks everyone. We will see come Tuesday when we are back on the road. We did clean the battery terminals just in case.

Funny thing...I usually drive with headlights on, but since it was so sunny that day, I forgot to turn them on....

Thanks again!

Paul

Our Knight does this too. It's not a problem.

With the generator running you were getting the 13/14 volts from the converter/inverter and not from the alternator.

Most likely your alternator is malfunctioning and giving you the warning light.

paulsang wrote:

wolfe10 wrote:
Was the generator on and powering the converter or inverter/charger? If so, turn off the 120 VAC breaker to it and see if this "solves" it.

Yes we were running the Generator as we rolled. So, where/what is this 120 VAC breaker? Would it be the switch by the door that kills everything in the coach?

Remember...spell it out...LOL Trying to figure the manuals out.

Monaco products have this "problem". It is NOT a REAL problem, but an annoyance. What happens when you have the engine running is this, the Alternator output is anywhere from 13.4 to 14.1 volts. When you turn the Gen set ON with the engine ON, the Inverter/Charger comes on and the BULK charge rate will be about 14.2 to 14.4 volts. THAT voltage is the Threshold for the ALT light to come ON. The Dash system has no way to know where the voltage comes from, it just "sees" that higher voltage. Once the Inverter/Charger goes to Float charge (usually within an hour), the higher voltage goes away and your Alt light goes out. A few things you can do to stop it
1. Turn on your headlights and Dash AC, That load usually drops the voltage below 14 volts
2. Turn the charger section of the Inverter OFF
3. The Monaco TSB fix is to install a Bosch relay between the Ignition charge signal wire that goes to the Charge solenoid for chassis charging of the Coach batteries. It is wired thru the hourmeter wire of the Gen set. What this does is when the Genset is ON, there is a 12 volt hot wire for the hourneter. This wire is used at the Bosch relay to KILL the dash engine charge wire to the solenoid. This means in transit, the Inverter/Charger is charging the coach batteries and the Engine Alternator is charging the chassis batteries. When you turn the Genset OFF the Bosch relay allows the Ignition wire to complete the circuit to the charge solenoid for the Alternator to charge BOTH battery banks.
There is NOTHING wrong with the Alt light coming on, it is just an annoyance. Doug

Our MH has done similar when running generator going down road. Whether it helped or was just coincedence, I cleaned house battery terminals and it hasn't done it anymore.

No, it would be in your 120 VAC breaker box.

The switch by the door is for the 12 VDC system.

Two competing charging sources can sometimes confuse each other. I now on our sailboat, if engine is started while still on shore power (converter on) you don't even get the tach to register.

wolfe10 wrote:
Was the generator on and powering the converter or inverter/charger? If so, turn off the 120 VAC breaker to it and see if this "solves" it.

Yes we were running the Generator as we rolled. So, where/what is this 120 VAC breaker? Would it be the switch by the door that kills everything in the coach?

Remember...spell it out...LOL Trying to figure the manuals out.

Was the generator on and powering the converter or inverter/charger? If so, turn off the 120 VAC breaker to it and see if this "solves" it.